Magnetic head having a notched pole piece structure and method of making the same

ABSTRACT

A magnetic head having an improved fringing field and overwrite capability, and a method of making the same, are described. The method includes the acts of frame plating a pedestal over a first pole piece; depositing an insulator over the first pole piece and plated pedestal; chemically mechanically polishing (CMP) the top of the insulator to expose a top of the plated pedestal; depositing a gap layer over the top of the insulator and plated pedestal; depositing a seed layer over the gap layer; forming a second pole piece over the seed layer; ion milling, using the second pole piece as a mask, such that end portions of the seed layer are removed and a central portion remains; reactive ion milling, using the central portion of the seed layer as a mask, such that end portions of the gap layer are removed and a central portion of the gap layer having a width that is greater than a width of the second pole piece is formed; and ion milling the plated pedestal, using the central portion of the gap layer as a mask, to form a central notched structure having angled side walls of 25 degrees±24 degrees relative to normal.

BACKGROUND OF THE INVENTION

This application is a divisional of application Ser. No. 10/105,119,filed Mar. 22, 2002.

1. Field of the Invention

This invention relates generally to magnetic heads in disk drives, andmore particularly to magnetic write heads with notched pole piecestructures and methods of making the same.

2. Description of the Related Art

A write head is typically combined with a magnetoresistive (MR) readhead to form a merged MR head, certain elements of which are exposed atan air bearing surface (ABS). The write head comprises first and secondpole pieces connected at a back gap that is recessed from the ABS. Thefirst and second pole pieces have first and second pole tips,respectively, which terminate at the ABS. An insulation stack, whichcomprises a plurality of insulation layers, is sandwiched between thefirst and second pole pieces, and a coil layer is embedded in theinsulation stack. A processing circuit is connected to the coil layerfor conducting write current through the coil layer which, in turn,induces write fields in the first and second pole pieces. A non-magneticgap layer is sandwiched between the first and second pole tips. Writefields of the first and second pole tips at the ABS fringe across thegap layer. In a magnetic disk drive, a magnetic disk is rotated adjacentto, and a short distance (fly height) from, the ABS so that the writefields magnetize the disk along circular tracks. The written circulartracks then contain information in the form of magnetized segments withfields detectable by the MR read head.

An MR read head includes an MR sensor sandwiched between first andsecond non-magnetic gap layers, and located at the ABS. The first andsecond gap layers and the MR sensor are sandwiched between first andsecond shield layers. In a merged MR head, the second shield layer andthe first pole piece are a common layer. The MR sensor detects magneticfields from the circular tracks of the rotating disk by a change inresistance that corresponds to the strength of the fields. A sensecurrent is conducted through the MR sensor, where changes in resistancecause voltage changes that are received by the processing circuitry asreadback signals.

One or more merged MR heads may be employed in a magnetic disk drive forreading and writing information on circular tracks of a rotating disk. Amerged MR head is mounted on a slider that is carried on a suspension.The suspension is mounted to an actuator which rotates the magnetic headto locations corresponding to desired tracks. As the disk rotates, anair layer (an “air bearing”) is generated between the rotating disk andan air bearing surface (ABS) of the slider. A force of the air bearingagainst the air bearing surface is opposed by an opposite loading forceof the suspension, causing the magnetic head to be suspended a slightdistance (flying height) from the surface of the disk. Flying heightsare typically on the order of about 0.05 μm.

The second pole, along with its second pole tip, is frame-plated on topof the gap layer. After depositing a seed layer on the gap layer, aphotoresist layer is spun on the seed layer, imaged with light, anddeveloped to provide an opening surrounded by a resist wall for platingthe second pole piece and second pole tip. To produce a second pole tipwith a narrow track width, the photoresist layer has to becorrespondingly thin.

Once the second pole tip is formed, it is desirable to notch the firstpole piece opposite the first and second bottom corners of the secondpole tip. Notching the first pole piece minimizes side writing in trackswritten on the magnetic disk. As is known, when the tracks areoverwritten by side writing the track density of the magnetic disk isreduced. When the first pole piece is notched, it has first and secondside walls that are aligned with first and second side walls of thesecond pole tip, so that the first pole piece and the second pole tiphave the same track width at the ABS. This minimizes fringing ofmagnetic fields from the second pole tip laterally beyond the trackwidth (side writing) to a wide expanse of the first pole piece.

A prior art process for notching the first pole piece entails ion beammilling the gap layer and the first pole piece, employing the secondpole tip as a mask. According to this prior art process (typified inU.S. Pat. No. 5,452,164 and U.S. Pat. No. 5,438,747), the gap layer istypically alumina, and the first and second pole pieces and pole tipsare typically Permalloy (NiFe). Alumina mills more slowly thanPermalloy; thus the top of second pole tip and a top surface of thefirst pole piece are milled more quickly than the gap layer. Further,during ion milling, there is significant redeposition of alumina onsurfaces of the workpiece. The milling ion beam is typically directed atan angle with respect to a normal to the layers, in order that millingand clean-up be done simultaneously.

Notching the first pole piece is very time consuming due, in part, toshadowing of the notch sites by the angled milling and by the profile ofthe second pole tip, as the wafer supporting the magnetic head isrotated. The length of milling time is due more, however, to the largelateral expanse of the first pole piece. Since the top and side walls ofthe second pole tip are also milled while the first pole piece is beingnotched, the second pole tip has to be formed with extra thickness andwidth so that, after notching is completed, the second pole tip is atits target height and target track width. Unfortunately, because of thelong time required for notching it is difficult to meet the targetswithin acceptable tolerances. This lowers the manufacturing yield. Also,the extra height of the initially formed second pole tip increases theaspect ratio and reduces the line width of the second pole tip.

In order to minimize overmilling of the first pole piece, anotherprocess removes the gap layer, except for a desired portion between thefirst and second pole tips, by a wet-etchant. After the unwantedportions of the gap layer are removed, the first pole piece is ionmilled, employing the second pole tip as a mask. This process eliminatessignificant redeposition of the alumina. A problem with this process,however, is that the etching undercuts the gap layer under the base ofthe second pole tip, which is a critical area for the transfer of fieldsignals. The undercut regions provide spaces where Permalloy can beredeposited during subsequent ion milling of the first pole piece, orother foreign material can be redeposited upon subsequent milling andclean-up steps. Further, if the track width of the second pole tip is inthe order of 1 am, the etchant may release the second pole tip from thegap layer, thus ruining the head.

Accordingly, what is needed is an improved method to make such magneticheads with better fringing fields and overwrite capabilities.

SUMMARY OF THE INVENTION

As described herein, a first aspect of the present invention involves amagnetic write head which has a unique pre-plated pedestal havingnotched angled side walls for providing a better fringing field andoverwrite capability. A second aspect of the present invention involvesa method of making such a magnetic head.

In accordance with the first inventive aspect, a magnetic head is madeof a first pole piece; a second pole piece; a unique pre-plated notchedstructure formed over a central portion of the first pole piece; and agap separating the notched structure from the second pole piece.Advantageously, the notched structure is formed with angled side wallsfor an improved fringing field and overwrite capability. Preferably, theangle of each angled side wall is 25 degrees±24 degrees relative tonormal. This notched structure may have a top straight-walled portionover the angled-walled portion, a bottom straight-walled portionunderneath the angled-walled portion, or both.

In accordance with the second inventive aspect, a method of making sucha magnetic head includes the acts of frame plating a pedestal over afirst pole piece; depositing an insulator over the first pole piece andplated pedestal; chemically mechanically polishing (CMP) the top ofinsulator to expose a top of the plated pedestal; depositing a gap layerover the top of insulator and plated pedestal; depositing a seed layerover the gap layer; forming a second pole piece over the seed layer; ionmilling, using the second pole piece as a mask, so that end portions ofthe seed layer are removed and a central portion remains; reactive ionmilling, using the central portion of the seed layer as a mask, suchthat end portions of the gap layer are removed and a central portion ofthe gap layer having a width that is greater than a width of the secondpole piece remains; and ion milling the plated pedestal, using thecentral portion of the gap layer as a mask, to form a central notchedstructure having the angled side walls. The angled side walls are formeddue to the shadowing effect and the decreasing size of the centralportion of the gap layer during the ion milling process.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and advantages of the presentinvention, as well as the preferred mode of use, reference should bemade to the following detailed description read in conjunction with theaccompanying drawings:

FIG. 1 is a planar view of an exemplary magnetic disk drive;

FIG. 2 is an end view of a slider with a magnetic head of the disk driveas seen in plane 11-11;

FIG. 3 is an elevation view of the magnetic disk drive wherein multipledisks and magnetic heads are employed;

FIG. 4 is an isometric illustration of an exemplary suspension systemfor supporting the slider and magnetic head;

FIG. 5 is a partial elevation view of the slider and magnetic head asseen in plane V-V of FIG. 2;

FIG. 6 is a top view of the second pole piece and coil layer, a portionof which is shown in FIG. 5, with all insulation material removed;

FIG. 7 is a partial ABS view of the slider taken along plane VII-VII ofFIG. 5 to show the read and write elements of the magnetic head;

FIG. 8 is an ABS of a prior art head prior to notching the first polepiece;

FIG. 9 is an ABS view of the prior art head of FIG. 8 after the firstpole piece is formed with notches by milling;

FIG. 10 is another ABS view of a prior art head formed with notches;

FIG. 11 is a magnetic head of the present invention;

FIG. 12 is the first of a series of illustrations which are used todescribed a method of making a magnetic head in accordance with thepresent invention, which shows the formation of a first pole piece;

FIG. 13 is an illustration of that shown in FIG. 12 except that a platedpedestal has been electrically plated over a central portion of thefirst pole piece;

FIG. 14 is an illustration of that shown in FIG. 13 except that aninsulator (e.g., alumina) has been deposited over the tops of the firstpole piece and the plated pedestal;

FIG. 15 is an illustration of that shown in FIG. 14 except that chemicalmechanical polishing (CMP) has been performed over the top of theinsulator to expose a top of the plated pedestal;

FIG. 16 is an illustration of that shown in FIG. 15 except that a gaplayer has been deposited over the top of plated pedestal and theinsulator;

FIG. 17 is an illustration of that shown in FIG. 16 except that a seedlayer has been deposited over the gap layer;

FIG. 18 is an illustration of that shown in FIG. 17 except that a secondpole piece has been plated and formed over the seed layer;

FIG. 19 is an illustration of that shown in FIG. 18 except that ionmilling has been performed using the second pole piece as a mask toremove end portions of the seed layer and to form a central portionthereof, and subsequent reactive ion milling has been performed usingthe central portion of the seed layer as a mask to remove end portionsof the gap layer and to form a central portion thereof;

FIG. 20 is an illustration of that shown in FIG. 19 except that ionmilling on the plated pedestal has been performed, using the centralportion of the gap layer as a mask, to form a central notched structurehaving angled side walls;

FIGS. 21-24 are other examples of a notched structure having angled sidewalls of the present invention; and

FIGS. 25-26 are other embodiments of a magnetic head of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description is the best embodiment presently contemplatedfor carrying out the present invention. This description is made for thepurpose of illustrating the general principles of the present inventionand is not meant to limit the inventive concepts claimed herein.

Referring now to the drawings, wherein like reference numerals designatelike or similar parts throughout the several views, there is illustratedin FIGS. 1-3 a magnetic disk drive 30. The drive 30 includes a spindle32 that supports and rotates a magnetic disk 34. The spindle 32 isrotated by a motor 36 that, in turn, is controlled by a motor controller38. A horizontal combined magnetic head 40 for reading and recording ismounted on a slider 42. The slider 42 is supported by a suspension 44and actuator arm 46. A plurality of disks, sliders and suspensions maybe employed in a large capacity direct access storage device (DASD), asshown in FIG. 3. The suspension 44 and actuator arm 46 position theslider 42 to locate the magnetic head 40 in a transducing relationshipwith a surface of the magnetic disk 34. When the disk 34 is rotated bythe motor 36, the slider is supported on a thin (typically, 0.05 μm)cushion of air (air bearing) between the disk and an air bearing surface(ABS) 48.

The magnetic head 40 may be employed for writing information to multiplecircular tracks on the surface of the disk 34, as well as for readinginformation therefrom. Processing circuitry 50 exchanges signalsrepresenting such information with the head 40, provides motor drivesignals, and also provides control signals for moving the slider 42 tovarious tracks. In FIGS. 1 and 4 the slider 42 is shown mounted to ahead gimbal assembly (HGA) 52 that is mounted to the suspension 44. Allof the above components are supported on a base 53.

FIG. 5 is a side cross-sectional elevation view of a mergedmagnetoresistive (MR) head 40, with a write head portion 54 and a readhead portion 56. The read head portion includes an MR sensor 58. The MRsensor 58 is sandwiched between first and second gap layers 60 and 62that are, in turn, sandwiched between first and second shield layers 64and 66. In response to external magnetic fields, the resistance of theMR sensor 58 changes. A sense current conducted through the sensorcauses these resistance changes to be manifested as potential changes,which are processed by the processing circuitry 50 shown in FIG. 3.

The write head portion 54 of the head includes a coil layer 68sandwiched between first and second insulation layers 70 and 72. A thirdinsulation layer 74 may be employed for planarizing the head toeliminate ripples in the second insulation layer caused by the coillayer 68. The first, second and third insulation layers are referred toas an “insulation stack”. The coil layer 68, and the first, second andthird insulation layers 70, 72 and 74, are sandwiched between first andsecond pole piece layers 76 and 78. The first and second pole piecelayers 76 and 78 are magnetically coupled at a back gap 80, and havefirst and second pole tips 82 and 84 that are separated by anon-magnetic gap layer 86 at the ABS. As shown in FIGS. 2 and 4, firstand second solder connections 88 and 90 connect leads (not shown) fromthe MR sensor 58 to leads 96 and 98 on the suspension 44; third andfourth solder connections 100 and 102 connect leads 104 and 106 from thecoil 68 (see FIG. 6) to leads 108 and 110 on the suspension.

FIG. 8 shows an ABS view of a prior art merged magnetic head, in whichthe second shield of the read head and the first pole piece of the writehead are a common layer 66/76. The gap layer 120 has been formed on thefirst pole piece layer 66/76, followed by frame plating a second poletip 122 on the gap layer 120. The second pole tip 122 is a front portionof the second pole piece. The second pole tip is bounded by a top 124,first and second side walls 126 and 128, and a base 130. The targettrack width (TW) is shown in FIG. 8. Since the first pole piece will benotched by ion milling, the second pole tip 122 is larger than a targetsize track width (TW) of the second pole tip, so as to allow forconsumption of the second pole tip during a subsequent milling cycle.Accordingly, before milling, the first and second side walls 126 and 128extend beyond the track width, and the top 124 is higher than the targetheight. The dimensions of these sacrificial portions is referred to inthe art as windage.

In FIG. 9 ion milling is employed to mill through the gap layer to forma write gap 130 with first and second side walls 132 and 134, and tomill notches into the first pole piece 66/76 with first and second sidewalls 136 and 138. After milling, the first side walls 126, 132 and 136are contiguous, and the second side walls 128, 134 and 138 arecontiguous. This notching improves the transfer of flux between thesecond pole tip 122 and the first pole piece 66/76, since the flux willtransfer to the pedestal portion of the first pole piece instead of thelarger expanse thereof. This reduces side writing by the write head. Themilling is at an angle to a normal to the layers 66/76 and 64 in orderto minimize redeposition of the milled material. It should be understoodthat the partially completed magnetic head in FIG. 9 rests upon asubstrate (not shown) that is rotated during the milling cycle. Thesecond pole tip is employed as a mask for forming the write gap 130 andnotching the first pole piece at 136 and 138. It can be seen that thiscauses shadowing at the notching sites 136 and 138 during approximately180 degrees of the rotation, due to the angle of the milling. Thisshadowing increases the processing time required to form the notches inthe first pole piece. It should be noted that the downward slopingportions of the first pole piece layer 62 in FIG. 9 are formed due tothe shadowing by the second pole tip 122.

After milling, the second pole tip 122 has been reduced in size. Withthe prior art method it is very difficult to reduce the second pole tip122 to the target track width and the target height because of thesignificant time required for milling the large lateral expanse of thefirst pole tip 66/76. Milling of flat surfaces is very time-consuming ascompared to side walls. Further, the top 124 in FIG. 8 requires extraheight because of the long time required for milling. This extra heightincreases the aspect ratio (ratio between height of resist employed toframe plate the second pole tip 122 and the target track width), whichreduces the line width of the second pole tip. Prior art methods ofnotching the first pole piece discussed in commonly assigned U.S. Pat.Nos. 5,438,747 and 5,452,164 indicate a strong-felt need to reduce thetime required for notching.

FIG. 10 shows another conventional magnetic head 1002, having a firstpole piece 1004 and a second pole piece 1006 separated by a gap 1008.Between first pole piece 1004 and gap 1008 is a notched structure 1010(PIN), which resides on raised and angled surface 1012 of first polepiece 1004. The surface 1012 is raised and angled due to the ion millingprocess to form the notches. Note that notched structure 1010 itself has“straight” side walls (i.e., side walls that are zero degrees relativeto normal).

In contrast with FIG. 10, FIG. 11 is one example of a magnetic head 1102having a notched pole piece structure in accordance with the presentinvention. Magnetic head 1102 includes a first pole piece 1104 (“P1”)and a second pole piece 1106 (“P2”) separated by a gap 1108. Betweenfirst pole piece 1104 and gap 1108 is a central notched structure 1110having angled side walls. By “angled,” it is meant that the side wallsslope outwardly at an angle greater than zero degrees (relative tonormal). The angle at which the side walls slope is preferably 25degrees, +24 degrees. In decreasing order of generality, the angle maybe 25 degrees±24 degrees; or 25 degrees±20 degrees; or 20 degrees±18degrees; or 20 degrees+10 degrees; or between about 5-50 degrees. It hasbeen observed that such angled side walls provide for an improvedfringing field and overwrite capability as compared to the straight sidewalls of notched structure 1010 of FIG. 10. In this example, notchedstructure 1110 actually is formed of a top straight-walled portion 1112having “straight” walls as well as a bottom angled-wall portion 1114having the angled side walls. Below the bottom angled-wall portion 1114,bottom surfaces of notched structure 1110 have small outward downwardslopes. As will be described below, the notched structure is made from apre-plated structure which is subsequently milled.

A method of making a magnetic head according to the present inventionwill now be described in relation to FIGS. 12-25. Beginning with FIG.12, a first pole piece 1202 (“P1”) is formed by frame plating. Firstpole piece 1202 is made of a magnetic material, preferably one with ahigh magnetic moment, such as nickel-iron (NiFe), cobalt (Co), orcobalt-iron-nitride (CoFeN). Next, in FIG. 13, a plated pedestal 1302(“N3”) is frame plated over a central portion of first pole piece 1202.Plated pedestal 1302 is made of a magnetic material, preferably one witha high magnetic moment, such as NiFe, Co, or CoFeN. Representativedimensions are shown in FIG. 13. Preferably, plated pedestal 1302 isplated to a thickness between about 1-4 μm, and preferably to athickness of about 2 μm. The width of plated pedestal 1302 is preferablygreater than 2 μm.

In FIG. 14, an insulator 1402 such as alumina (Al₂O₃) is then depositedover first pole piece 1202 and plated pedestal 1302. Preferably, in thisembodiment insulator 1402 is deposited to a thickness that is abouttwice the thickness of plated pedestal 1302. Next, in FIG. 15, chemicalmechanical polishing (CMP) is performed to expose a top 1502 of platedpedestal 1302 such that the top surfaces of both insulator 1402 andplated pedestal 1302 are flush, flat, and smooth.

In FIG. 16, a gap layer 1602 (“gap”) is then deposited over the flat topsurface of insulator 1402 and plated pedestal 1302. Gap layer 1602 maybe made of alumina (Al₂O₃) or other suitable dielectric material. Thethickness of gap layer 1602 preferably varies between about 1000 and2000 Angstroms, and in the present example it has a thickness of about1600 Angstroms. In FIG. 17, a seed layer 1702 (“seed”) is deposited overgap layer 1602. Seed layer 1702 is made of a magnetic material, andpreferably one with a high magnetic moment, such as a NiFe, Co, orCoFeN. The thickness of seed layer 1702 preferably varies between about400 and 4000 Angstroms, and in the present example it has a thickness ofabout 800 Angstroms.

Once gap layer 1602 and seed layer 1702 are deposited, a second polepiece 1802 (“P2”) is plated and formed over a central portion of seedlayer 1702 as shown in FIG. 18. This is done using well-known frameplating and photolithography techniques. As with first pole piece 1202,plated pedestal 1302, and seed layer 1702, second pole piece 1802 ismade of a magnetic material, preferably one with a high magnetic moment,such as NiFe, Co, or CoFeN.

End portions of seed layer 1702 are then ion milled using second polepiece 1802 as a milling mask to leave a remaining central portion ofseed layer 1902 (see FIG. 19) underneath second pole piece 1802. Giventhe dimensions of the present example, it may take about 3 to 10 minutesof ion milling time to form central portion 1902. Next, end portions ofgap layer 1602 are reactive ion milled using central portion 1902 ofseed layer as a milling mask to leave a remaining central portion 2002of gap layer (see FIG. 19). Given the dimensions of the present example,it takes less than 10 minutes of reactive ion milling time to formcentral portion 2002 (which of course ultimately depends on the initialgap thickness, which here is between 0.4 and 2 μm). Any suitable gas canbe utilized for the reactive ion milling, such as a mixture of argon gasand CHF₃, Freon, CH₂F₂, etc. In the present example, the gap layer isreactive ion milled until central portion 2002 has a width of about0.3-1.0 μm.

Further ion milling through plated pedestal 1302 and alumina 1402 isperformed to form a central notched structure 2102 shown in FIG. 20. Dueto shadowing effects, and since central portion 2002 of gap layer (FIG.19) is relatively wide and shrinks both in width and thickness duringthe milling process, plated pedestal 1302 is formed into notchedstructure 2102 shown in FIG. 20. This figure is the same as that shownin FIG. 11. As shown in FIG. 20, notched structure 2102 has anangled-wall portion 2104. Preferably, the angle of each side wall ofangled-wall portion 2104 is about 25 degrees+24 degrees. Once the widthof central portion 2002 is the same as width of second pole piece 1802,ion milling may be continued using second pole piece 1802 as a millingmask to form a straight-walled portion 2106 of notched structure 2104.Thus, central portion 1902 of seed layer (FIG. 19) is utilized as themask during ion milling to form central portion 2002 of gap layer, whichis subsequently used as the mask during ion milling of plated pedestal1302 to form notched structure 2102 (FIG. 20).

The notched structure which is formed may take on a variety of shapesand dimensions, as shown in FIGS. 21-24. FIG. 21 shows a notchedstructure 2608 formed on a first pole piece 2602 which is adjacent asecond pole piece 2604. As shown, notched structure 2608 has a bottomstraight-walled structure, a middle angled-wall portion, and a topstraight-walled portion. The angle of each angled side wall of theangled-wall portion is preferably 25 degrees±24 degrees. Notchedstructure 2608 has a total height 2610 of 0.1-0.5 μm, where the middleangled-wall and top straight-walled portions have a combined height 2612of 0.3 μm and the top straight-walled portion alone has a height 2614 ofless than 0.1 μm. The thickness of the gap is about 0.12 μm. The bottomstraight-walled portion has a width that is much greater than the widthof the angled-wall portion (e.g., 4 μm+the width of second pole piece2604). The bottom straight-walled portion may alternatively have endsthat extend all the way over the ends of first pole piece 2602. The topstraight-walled portion has a width that is substantially the same asthe width of second pole piece 2604.

As another example, FIG. 22 shows a notched structure 2708 formed on afirst pole piece 2702 which is adjacent a second pole piece 2704. Asshown, notched structure 2708 has a bottom portion, a middlestraight-walled portion, and a top angled-wall portion. Nostraight-walled portion above the top angled-wall portion is formed. Theangle of each angled side wall of the top angled-wall portion is 25degrees±24 degrees. Notched structure 2708 has a total height 2709 of1-5 μm; the middle straight-walled portion and the top angled-wallportion have a combined height 2710 of 0.24 μm; and the top angled-wallportion alone has a height of 0.1-0.5 μm. The thickness of the gap isabout 0.12 μm. The middle straight-walled portion has a width that isequal to the width of the bottom of the angled-wall portion, and thebottom portion has ends that extend over the ends of second pole piece2702.

In yet even another example, FIG. 23 shows a notched structure 2808formed on a first pole piece 2802 which is adjacent a second pole piece2804. As shown, notched structure 2808 has a bottom portion, middlestraight-walled portion, a middle angled-wall portion, and a topstraight-walled portion. The angle of each angled side wall of themiddle angled-wall portion is 25 degrees±24 degrees. Notched structure2808 has a total height 2809 of 1-5 μm, where the middle and topportions have a combined height 2810 of 0.24 μm, the middle angled-wallportion and top straight-walled portion have a combined height 2812 of0.1-0.5 μm and the top straight-walled portion alone has a height 2814of 0-0.4 μm. The thickness of the gap is about 0.12 μm. The middlestraight-walled portion has a width that is equal to the width of thebottom of the middle angled-wall portion. The top straight-walledportion has a width that is substantially the same as the width ofsecond pole piece 2804.

As a final example of this type, FIG. 24 shows a notched structure 2908formed on a first pole piece 2902 which is adjacent a second pole piece2904. As shown, notched structure 2908 has a bottom portion and a topangled-walled portion. The angle of each angled side wall of the topangled-wall portion is preferably 25 degrees+24 degrees. Notchedstructure 2908 has a total height 2909 of 1-5 μm, where the topangled-wall portion alone has a height 2910 of about 1.5 μm. Thethickness of the gap is about 0.16 μm. The top of the top angled-wallportion has a width that is substantially the same as the width ofsecond pole piece 2904.

FIGS. 25-26 show another write head with a notched structure in analternate embodiment. A first pole piece 3004 is formed over a shield3002 and an notched structure 3006 having an angled-walled portion 3008is formed over first pole piece 3004. A second pole piece 3010 isseparated from notched structure 3006 by a gap 3007 and is adjacent athird pole piece 3012. Third pole piece 3012, which is frame plated oversecond pole piece 3010, also has an angled notched structure and isseparated from second pole piece 3010 by a seed layer. The magnetic headin FIG. 31 is the same as that in FIG. 30 except that it is recessedfrom second pole piece 3010.

Thus, a magnetic head and a method of making the same have beendescribed. The magnetic head includes a first pole piece; a second polepiece; a unique pre-plated notched structure formed over a centralportion of the first pole piece; and a gap separating the notchedstructure from the second pole piece. Advantageously, the notchedstructure has angled side walls to provide for an improved fringingfield and overwrite capability for the magnetic head. The angles of theside walls (relative to normal) may be 25 degrees±24 degrees; 25degrees±20 degrees; 20 degrees±15 degrees; 20 degrees+10 degrees; orbetween about 5-50 degrees. The notched structure may include a topstraight-walled portion over the angled-walled portion; a bottomstraight-walled portion underneath the angled-walled portion; or both.

The method of making such a magnetic head may include the acts of frameplating a pedestal over a first pole piece; depositing an insulator overthe first pole piece and plated pedestal; chemically mechanicallypolishing (CMP) the top of insulator to expose a top of the platedpedestal; depositing a gap layer over the top of insulator and platedpedestal; depositing a seed layer over the gap layer; forming a secondpole piece over the seed layer; ion milling, using the second pole pieceas a mask, so that end portions of the seed layer are removed and acentral portion remains; reactive ion milling, using the central portionof the seed layer as a mask, such that end portions of the gap layer areremoved and a central portion of the gap layer having a width that isgreater than a width of the second pole piece is formed; and ion millingthe plated pedestal, using the central portion of the gap layer as amask, to form a central notched structure having angled side walls.

It is to be understood that the above is merely a description ofpreferred embodiments of the invention and that various changes,alterations, and variations may be made without departing from the truespirit and scope of the invention as set for in the appended claims.None of the terms or phrases in the specification and claims has beengiven any special particular meaning different from the plain languagemeaning to those skilled in the art, and therefore the specification isnot to be used to define terms in an unduly narrow sense.

1. A magnetic head, comprising: a first pole piece; a second pole piece;a pre-plated pedestal formed over a central portion of the first polepiece; a gap separating the pre-plated pedestal from the second polepiece; and the pre-plated pedestal being notched with angled side walls.2. The magnetic head of claim 1, wherein each angled side wall of thepre-plated pedestal forms an angle of 25 degrees±24 degrees relative tonormal.
 3. The magnetic head of claim 1, wherein each angled side wallof the pre-plated pedestal forms an angle of 25 degrees±20 degreesrelative to normal.
 4. The magnetic head of claim 1, wherein each angledside wall of the pre-plated pedestal forms an angle of 20 degrees+/−15degrees relative to normal.
 5. The magnetic head of claim 1, whereineach angled side wall of the pre-plated pedestal forms an angle betweenabout 5-50 degrees relative to normal.
 6. The magnetic head of claim 3,wherein the first and the second pole pieces and the pre-plated pedestalcomprise magnetic material, and the gap comprises an insulator.
 7. Themagnetic head of claim 3, wherein an angled-walled portion of thepre-plated pedestal has the angled side walls, the magnetic head furthercomprising: a top straight-walled portion over the angled-walledportion.
 8. The magnetic head of claim 3, wherein an angled-walledportion of the pre-plated pedestal has the angled side walls, themagnetic head further comprising: a bottom straight-walled portionunderneath the angled-walled portion.
 9. The magnetic head of claim 3,wherein an angled-walled portion of the pre-plated pedestal has theangled side walls, the magnetic head further comprising: a topstraight-walled portion over the angled-walled portion; and a bottomstraight-walled portion underneath the angled-walled portion.
 10. A diskdrive, comprising: a magnetic head for writing to one or more disks; themagnetic head including: a first pole piece; a second pole piece; apre-plated pedestal formed over a central portion of the first polepiece; a gap separating the pre-plated pedestal from the second polepiece; and the pre-plated pedestal being notched with angled side walls.11. The disk drive of claim 10, wherein each angled side wall forms anangle of 25 degrees±24 degrees relative to normal.
 12. The disk drive ofclaim 10, wherein each angled side wall forms an angle of 25 degrees±20degrees relative to normal.
 13. The disk drive of claim 10, wherein eachangled side wall forms an angle of 20 degrees+/−15 degrees relative tonormal.
 14. The disk drive of claim 10, wherein each angled side wallhas an angle between about 5-50 degrees relative to normal.
 15. The diskdrive of claim 12, wherein the first and the second pole pieces and thepre-plated pedestal comprise magnetic material, and the gap comprises aninsulator.
 16. The disk drive of claim 12, wherein an angled-walledportion of the pre-plated pedestal has the angled side walls, themagnetic head further comprising: a top straight-walled portion over theangled-walled portion.
 17. The magnetic head of claim 12, wherein anangled-walled portion of the pre-plated pedestal has the angled sidewalls, the magnetic head further comprising: a bottom straight-walledportion underneath the angled-walled portion.
 18. The magnetic head ofclaim 12, wherein an angled-walled portion of the pre-plated pedestalhas the angled side walls, the magnetic head further comprising: a topstraight-walled portion over the angled-walled portion; and a bottomstraight-walled portion underneath the angled-walled portion.